Properly test border sampling for cube map textures on ES.
Properly test border sampling for cube map textures on ES.

Not sure why I did not do that. The NV_texture_border_clamp extension
does not mention any restriction to 2D/3D textures.

DerThorsten/magnum,DerThorsten/magnum,MiUishadow/magnum,ashimidashajia/magnum,ashimidashajia/magnum,MiUishadow/magnum,DerThorsten/magnum,MiUishadow/magnum,MiUishadow/magnum,MiUishadow/magnum,DerThorsten/magnum,ashimidashajia/magnum,ashimidashajia/magnum,MiUishadow/magnum,DerThorsten/magnum,ashimidashajia/magnum